1. Field of the Invention
The present invention relates to controlling the flow of fuel through an injector.
2. Background Art
Fuel injectors provide controlled pulses of fuel for combustion in internal combustion engines. The flow of fuel through a fuel injector may be controlled by one or more solenoids that open ports, close ports, or otherwise affect the flow of fuel within the fuel injector through movement of an armature. Typically, each solenoid armature is biased in a first position by a mechanical spring and activated to a second position by a motive force provided by a solenoid electromagnet. When the motive force is removed, the spring returns the solenoid armature to its deactivated position. This deactivation results in ringing of the armature or other mechanical vibrations due to contact with a mechanical stop. Such vibrations interfere with or otherwise complicate the control of fuel flowing through the injector and may shorten the effective injector life.
What is needed is to minimize ringing and other vibrations caused by deactivation of a control solenoid within a fuel injector.
The present invention utilizes a fluid in a chamber, through which a fuel control armature is moving, to dampen armature vibrations. This dampening effect is achieved by forming a passage through which the fluid flows as the actuator moves to a deactivated or steady state position.
A control module for controlling fuel delivery in a fuel injector is provided. The control module includes a control module housing defining a cavity. An armature is disposed at least partially within the cavity. The armature affects the flow of fuel by changing the area of a fuel port through which fuel passes. The control module includes a drive for moving the armature towards a contact wall of the cavity. The drive may include mechanical elements, such as a spring, electromagnetic elements, hydraulic elements, and the like. A fluid passage is formed as the armature moves towards the contact wall. The fluid passage remains open to pass a minimum volume of fluid when the armature contacts the contact wall. Vibrations in the armature are dampened by the fluid as fluid moves through the passage.
In an embodiment of the present invention, the fluid passage is formed by a dampener sleeve extending from the armature towards the contact wall. A stop may extend from the armature towards the contact wall farther than the dampener sleeve such that, when the stop contacts the wall, the fluid passage forms a minimum passage gap between the dampener sleeve and the contact wall. Alternatively, or in addition to the gap provided by the stop, the fluid passage may be formed by at least one notch or hole in the dampener sleeve.
In another embodiment of the present invention, the fluid passage is formed by a channel in the contact wall.
In yet another embodiment of the present invention, the fluid passage is formed between a dampener shim on the contact wall and a compression side of the armature. The compression side may be circular and the dampener shim may define a circular opening having an opening radius smaller than the compression side radius. A stop may extend from the compression side towards the contact wall a distance greater than the thickness of the dampener shim.
In still another embodiment of the present invention, the armature defines a shoulder at least partially around the armature. The fluid passage is formed between a dampener sleeve extending from the contact wall and the shoulder.
In a further embodiment of the present invention, the control module may define a second cavity within which is at least partially disposed a second armature. The second armature forms a second fluid passage. Fluid exiting the second armature cavity through the second fluid passage provides dampening of the second armature.
A method of controlling a flow of fuel in a fuel injector is also provided. At least a portion of an armature in a cavity containing fluid is moved. An opening area of a fuel port changes through the movement of the armature to affect the flow of fuel. A fluid passage for passing fluid between the armature and a wall defining the cavity is formed as the armature moves into contact with the wall. Fluid pressure increases as the fluid passage forms to dampen armature vibration.
A fuel injector is also provided. The fuel injector includes an injector body defining a fuel outlet. A fuel delivery path delivers pressurized fuel to the outlet. A control module connected to the fuel delivery path has at least one solenoid for controlling fuel delivery. Each solenoid has an armature biased by a spring to contact a wall defining a cavity when the solenoid is not energized. The armature and the wall form a passage as the armature approaches the wall. This passage passes fluid from between the armature and the wall into the remaining cavity to dampen vibrations caused by the armature contacting the wall.
A method of injecting fuel into an engine is also provided. The fuel is compressed. The compressed fuel is supplied to an opening in an injector through a controlled path. A solenoid in the injector is activated to control the flow of fuel along the path. The solenoid has an armature traveling through a fluid containing cavity. The solenoid, when deactivated, allows the armature to contact a wall defining the cavity. A passage is formed as the armature contacts the wall. Fluid is passed from between the armature and the wall resulting in dampened vibrations.